There are various types of electrically operated implantable medical devices for treating specific diseases and/or physical disorders. For example, one type of electrically operated implantable medical device is a cardiac pacemaker, which can be used, e.g., to restore a sick human heart to a normal rhythm. Another type of electrically operated implantable medical device is a neural stimulator, which can be used, e.g., to stimulate a patient's spinal cord or brain to treat various disorders, including, but not limited to, pain or epileptic seizures. For example, a neural stimulator can be a spinal cord stimulator (SCS) that treats chronic pain by delivering stimulation pulses to a patients spinal cord to induce paresthesia in regions of a patient's body that are afflicted by chronic pain. Other types of implantable neural stimulators include devices that deliver deep brain stimulation, cortical stimulation, cochlear nerve stimulation, peripheral nerve stimulation, vagal nerve stimulation, sacral nerve stimulation, and the like. Other examples of electrically operated implantable medical devices include, but are not limited to, infusion pumps for subcutaneously drug delivery (such as insulin pump), and diagnostic devices for monitoring a patient's condition.
An electrically operated implantable medical device needs a power source. Some electrically operated implantable medical devices are powered by a non-rechargeable battery. When the battery of such a device is depleted, the device must be explanted such that its battery can be replaced or a new device with a new battery can be implanted. Other electrically operated implantable medical devices include rechargeable batteries. The rechargeable battery of such a device can be recharged using a non-implanted device. For example, the implantable device and the non-implanted device can include coils that enable power to be wirelessly transferred, through a patient's skin, from the non-implanted device to the implantable device for the purpose of charging the rechargeable battery. Still other electrically operated implantable medical devices do not include any batteries, but rather, include coils that enable power to be wirelessly transferred, through a patient's skin, from the non-implanted device to the implantable device for the purpose of powering the implantable device. There also exist some electrically operated implantable medical devices that can be directly powered by non-implanted devices, when such a non-implanted device is in range, and can fall back on using their rechargeable battery when the non-implanted device is out of range.
Many electrically operated implantable medical devices are capable of communicating with a non-implanted device, such as a non-implanted programmer. Such electrically operated implantable medical device and non-implanted programmers often include coils that enable communication signals to be wirelessly transferred therebetween through a patient's skin.
Some electrically operated implantable medical devices include a first coil that is used to receive power from a non-implanted device, and a second coil that is used to receive communication signals from a non-implanted device. Other electrically operated implantable medical devices use the same coil for receiving power from a non-implanted device as well as receiving communication signal from a non-implanted device.